Problem: Simplify the following expression: $y = \dfrac{5n + 9}{8} \div \dfrac{10n}{5}$
Answer: Dividing by an expression is the same as multiplying by its inverse. $y = \dfrac{5n + 9}{8} \times \dfrac{5}{10n}$ When multiplying fractions, we multiply the numerators and the denominators. $y = \dfrac{ (5n + 9) \times 5 } { 8 \times 10n}$ $y = \dfrac{25n + 45}{80n}$ Simplify: $y = \dfrac{5n + 9}{16n}$